Which of the following traits is only passed from father to son?

The correct choice refers to Y-linked traits, which are exclusively passed from father to son. This is because the Y chromosome is one of the two sex chromosomes, with males having one X and one Y chromosome (XY). When a father passes his Y chromosome to his son, he is transmitting any traits encoded on that Y chromosome to his offspring.

In contrast, traits that are X-linked, whether recessive or dominant, can be passed from fathers to daughters as well as sons because females inherit one X chromosome from each parent (thus, a father with an X-linked trait can pass the trait to his daughters via his X chromosome). Autosomal traits, regardless of whether they are dominant or recessive, are inherited from any parent and can affect both sexes equally, so they do not have a father-to-son exclusivity. Therefore, the unique inheritance pattern of Y-linked traits distinguishes them as the only traits that pass strictly from father to son.